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May 4, 2007

Using Rocks as Time Machines

Clare M. Williams,
a graduate student in the MIT/WHOI Joint Program, examines
a rock collected from the seafloor to analyze its magnetic
properties. Magnetism
lets her unravel the patterns of lava flows to learn how ocean crust
builds up over time. “We know that lava flows come out onto the
seafloor periodically, at different spots, to build up crust,” said
Williams. “You can tell an old flow [which has a lower-intensity
magnetic signal] from a new flow.” (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)